After examining the BCEL source code (which was, at least for
SyntheticRepository and ClassPath, a pretty nice experience) I have
discovered that the SyntheticRepository implementation uses
ClassPath.getInputStream(...) to obtain the binary.
ClassPath.getInputStream(...) does not check the provided paths first;
it checks the current system classloader.
Fortunately, ClassPath.getClassFile(...) errors out if the class is not
in the explicitly-specified classpath entries. This means I should be
able to write my own Repository implementation to get things working for
my specific project. I just wanted to leave this explanation for anyone
who might stumble into it in the archives. :)
Cheers, and thanks again for the impressive library!
- Zachary Palmer
Hi, all. I'm new to both the list and to BCEL, but it looks like
precisely what I need for a research project on which I'm working. I
need reflective access to the .class files which are on a given
classpath without loading them into my JVM, so I've been experimenting
with SyntheticRepository and ClassPath. I've written small test app
and I'm getting results other than what I would expect. (e-mail
continues below the following source)
import org.apache.bcel.classfile.JavaClass;
import org.apache.bcel.util.ClassPath;
import org.apache.bcel.util.Repository;
import org.apache.bcel.util.SyntheticRepository;
public class BCELTest
{
public static void main(String[] arg) throws Exception
{
ClassPath cp = new ClassPath("/some/path/bin1");
System.out.println(cp);
Repository repo = SyntheticRepository.getInstance(cp);
repo.clear();
test(repo, "Test");
test(repo, "BCELTest");
}
public static void test(Repository repo, String className) throws
Exception
{
JavaClass jc = repo.loadClass(className);
System.out.println("==============================================");
System.out.println(jc);
}
}
The BCELTest.class binary is located in /some/path/bin2; a
hello-world-style Test.class binary is located in /some/path/bin1. I
would expect the above program to run the first test successfully
(loading Test.class and printing a summary of it) and then choke on
the second (since /some/path/bin2 is not in the ClassPath I
provided). However, my little test application successfully loads
both classes. Why is this?
For the purposes of my project, I need to be able to reflectively
analyze classes on a specified classpath (such as might be used when
invoking the Java compiler) without accidentally polluting it with my
own JVM's classpath. The above behavior has me a bit confused. Am I
going about things wrong? Any suggestions are welcome.
And by the way, thanks for the incredible library. :) If all goes
well, I'll have something to add to the "BCEL Projects" list.
Cheers,
Zachary Palmer
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